For the two commercial companies contracted with NASA for cargo resupply of the International Space Station, 2015 could have been a year marked entirely by the risk that eventually catches all space companies. Instead, for SpaceX and Orbital ATK, 2015 marked an astounding resurgence and recovery from launch mishaps, ending in December with the return of Orbital ATK’s Cygnus and the unprecedented success of a first stage Falcon 9 rocket landing back on land.
Orbital ATK: Cygnus flies on Atlas V; Wallops prepares for return of Antares
Orbital ATK began 2015 where no space company wants to be: recovering from a devastating launch mishap in October 2014 that claimed its Antares launch vehicle and Cygnus spacecraft.
While damage to the Mid-Atlantic Regional Spaceport’s launch pad 0A was extensive and required nearly a year’s worth of repairs, Orbital ATK turned toward the redundant nature of Cygnus to launch the spacecraft on a rocket other than Antares as repairs to the launchpad and upgrades to Antares took place.
To this end, Orbital ATK contracted with United Launch Alliance (ULA) for use of their veteran Atlas V rocket for two Cygnus missions, the first of which was set for 2015.
Working around an already busy 2015 launch schedule for ULA (the company saw a total of 12 launches, nine of which occurred on the Atlas V), a late-in-the-year launch window was selected for the Cygnus OA-4 mission.
With the launch date finally selected for 3 December, the new version of the Enhanced Cygnus module completed all pre-launch processing activities at its various locations before being enclosed in its launch shroud and transported to LC-41 at the Cape Canaveral Air Force Station where it was hoisted atop the 401 configuration Atlas V rocket.
The launch campaign on 3 December was scrubbed at the end of the launch window due to a heavy band of rain draped across the Cape.
A subsequent launch attempt on 4 December was scrubbed multiple times in the terminal count due to high wind violations at the launch pad.
The launch represented the 60th flight of the Atlas V rocket and its 60th straight success from a customer standpoint and also marked the first time that two commercial companies collaborated for the launch of a resupply mission to the International Space Station (ISS).
The flight also marked ULA’s first mission to the ISS and marked a resumption of commercial cargo resupply efforts to the Station following the loss of the SpaceX CRS-7 mission during launch in June.
Two and a half days after liftoff, Cygnus successfully rendezvoused with the ISS and was berthed to the orbiting outpost by NASA astronaut Kjell Lindgren, officially returning Cygnus to active ISS resupply duties and becoming the first U.S. spacecraft to reach the Space Station since April 2015 (SpaceX’s CRS-6 mission).
The second contracted flight of Cygnus on the Atlas V is currently set for 10 March 2016 at 05:00 UTC (00:00 EST – or 12:00 a.m. midnight EST) on the OA-6 mission, which will fly before the OA-5 mission.
The OA-5 mission will see the Return To Flight of the Antares rocket from the Mid-Atlantic Regional Spaceport in Virginia and a resumption of Cygnus flights on Orbital ATK’s dedicated vehicle.
OA-5 is currently targeting a tentative launch date of No Earlier Than 31 May 2016 pending final checkouts and test firings of the upgraded Antares first stage.
SpaceX: From almost landings to failure to most-memorable Return To Flight
For SpaceX, 2015 began with the early January launch of the CRS-5 resupply mission to the ISS.
The flight represented yet another successful resupply effort from SpaceX as well as the much-anticipated first attempt to land the first stage of the Falcon 9 on a floating barge in the Atlantic Ocean.
The landing attempt on CRS-5 followed a series of scaled tests at the SpaceX’s test site in McGregor, Texas, as well as in-flight, soft-touchdown-in-the-water tests during the CASSIOPE and Thaicom-6 satellite launches as well as the CRS-3 mission to the ISS.
All of these tests quickly gave SpaceX valuable in-flight data on how the first stage performed during the series of post-separation burns needed to bring it to a specific, pin-point location for a soft touchdown.
With each successive test, SpaceX updated the systems and hardware on each follow-on Falcon 9 v1.1 stages to incorporate the lessons learned.
These changes culminated in January with the company’s first attempt to land the first stage on the Autonomous Spaceport Drone Ship (ASDS).
The landing, by all accounts, came much closer to success than anyone could have predicted, with the stage making it to ASDS, but at an angle, before tumbling over the side of the drone ship into the ocean.
SpaceX increased the hydraulic fluid supply before the next landing attempt in February following the successful completion of the first stage’s role in the launch of the Deep Space Climate Observatory spacecraft into orbit.
Poor sea conditions impacted the ASDS’s ability to receive the stage, resulting in SpaceX opting to call off the landing attempt, instead allowing the stage to conduct another soft landing in the ocean.
Nonetheless, the soft water landing showed that the stage returned through its re-entry and landing burns with good stability.
Furthermore, this landing was stable and precise – with SpaceX noting that it might have resulted in a good landing had the ASDS been able to receive it.
Nonetheless, SpaceX again analyzed the data transmitted from the stage and made yet further enhancements to Falcon 9 v1.1 stage’s landing systems and hardware.
These improvements paved the way for the next attempt to land the first stage on the ASDS during the CRS-6 mission in April.
Following the successful launch of CRS-6 (yet another successful resupply effort for ISS from SpaceX), the first stage fired through its sequences of maneuvers and rocket engine firings to aim itself for the ASDS barge.
And this landing attempt came even closer to success than the first barge landing attempt on CRS-5.
During the CRS-6 landing attempt, the first stage successfully found the ASDS barge and performed a soft landing with just a bit too much lateral velocity.
As both up-close and long-range tracking video of the landing attempt released by SpaceX showed, thrusters at the top of the stage tried to mitigate the lateral movement of the stage at landing.
However, the stage eventually lost its fight with gravity, having come down on only two of its four landing legs, and tipped over – resulting in the destruction of the first stage but a very close-to-successful landing attempt.
Nonetheless, the fact that the first stage had now found the barge on both of its successive barge-landing attempts was a feat few anticipated and marked steady progress toward SpaceX’s desire to recover the first stage of the Falcon 9 rocket and eventually prove to the U.S. Federal Aviation Administration (FAA) that the stages could safely and reliably return to land at the Cape Canaveral Air Force Station (CCAFS).
With data and analysis from the CRS-6 landing attempt in hand, SpaceX made yet further modifications to the landing hardware and software and announced that they would try again to land on ASDS on the scheduled June CRS-7 launch to the ISS.
The 19th mission of the Falcon 9 ended abruptly during first stage flight 2 minutes 19 seconds after liftoff when a failure of the second stage resulted in the loss of the launch vehicle and cargo.
Loss of the Falcon 9 brought to bear a situation that many in the space industry hoped would never happen: Both of the commercial companies contracted with NASA for resupply of the ISS were now grounded from separate accidents.
However, SpaceX – like Orbital ATK – quickly traced the cause of the failure: a strut securing a helium bottle in the second stage LOX tank failed, causing the helium pressurization system to flood the LOX tank with excess helium – which in turn led to an over pressurization and failure of the LOX tank.
To the shock of many, SpaceX quickly announced that recovery efforts were anticipated to take roughly six months, and that the company was aiming to return the Falcon 9 to active service before the end of the calendar year – something which many considered improbable.
But SpaceX proved once again that the company takes improbable and makes it possible.
With recovery efforts on going, SpaceX announced a dual nature to the return to flight mission, eventually selected to be the ORBCOMM-2 flight.
In short, SpaceX wasn’t planning to return the Falcon 9 to flight by simply delivering a payload to orbit.
Instead, the company aimed to not only place all 11 ORBCOMM satellites successfully into orbit but also return the Falcon 9 first stage directly to land at Landing Zone-1 (LZ-1) at the CCAFS.
This once again came as a surprise to many who assumed that the FAA would not grant SpaceX permission to return the first stage to land until the company had successfully demonstrated that the stages could land on the ASDS.
However, the FAA approved of SpaceX’s data and the changes made in the stand-down period to the flight software as well as hardware needed to successfully land the first stage.
Based on this and the success of the two previous ASDS landings that actually made it to the barge, the FAA agreed to allow SpaceX to attempt to land the Falcon 9 first stage back at LZ-1.
However, many things, including the launch date for the mission, still remained inconclusive.
Finally, a mid-December target launch date was selected following the successful test of the ORBCOMM-2 Falcon 9 first stage at the McGregor, Texas, test facility and subsequent shipment of the stage to the Cape.
After a successful hot fire test at LC-40, SpaceX selected a return to flight launch date of 20 December.
On 19 December, after consulting weather forecasts for both launch and landing, SpaceX decided to postpone the launch to 21 December to obtain more favorable landing weather conditions.
However, SpaceX wasn’t simply returning to flight with the same version of the Falcon 9 first stage used on CRS-7.
Instead, the company chose to return to flight with the Falcon 9 v1.1 Full Thrust variant, a slightly longer rocket with upgraded and stretched fuel tanks to accommodate a new type of super-chilled oxidizer and propellant.
The new super-chilled propellant and oxidizer would allow the vehicle to gain better performance for the multitude of objectives Falcon 9 will be tasked with in the future.
Importantly, it also meant significant changes to the countdown procedures and timeline leading up to the launch.
Unlike most rockets which are fueled a few hours before liftoff and subsequently have their propellant tanks replenished during the final minutes of the count, the Falcon 9 Full Thrust would see actual full-scale propellant loading run all the way until three or two minutes prior to liftoff.
This, combined with the fact that this was a return to flight mission and a brand new version of the Falcon 9, seemingly stacked the odds against an on-time liftoff on the first attempt.
But SpaceX once again proved the odds wrong.
With fueling of the Falcon 9 second stage running right up until almost T-2mins and counting, Falcon 9 effortlessly sailed through her countdown and roared to life at 20:29 EST on 21 December.
But while the second stage successfully deployed and completed the primary mission objective of the ORBCOMM-2 mission, all eyes were at the Cape.
After successfully conducting its first stage burn and separating from the remainder of the launch vehicle, the first stage of the Falcon 9 fired its thrusters to flip itself around – with its engines pointing in the direction of travel.
The rocket then fired three of its nine engines to performed the Boost Back burn to begin its return to the Cape.
Just a few minutes prior to landing, the stage once again fired three of its nine engines to perform the Entry Burn, slowing the stage and altering its trajectory to begin a precision aim for LZ-1.
Then, with less than a minute to go, Falcon 9 fired only one of its nine engines to perform a continuous Landing Burn, which saw the stage slow its extremely fast and steep descent and use its flight software and navigation tools to aim for the dead center of LZ-1.
Heralding its return with the telltale sonic booms absent from the Cape since the final landing of the Shuttle on 21 July 2011 (exactly 4 years and 5 months to the day), the first stage of the Falcon 9 rocket descended gracefully and what appeared to be effortlessly right onto the center of LZ-1.
Then, 9mins 45seconds after launch, the single rocket engine powering the stage’s descent cut out and the stage stood proudly and securely on the ground.
SpaceX had achieved what no other company had – the successful fly-back and return under rocket-powered flight of the first stage of an orbital rocket launch vehicle to its launch site.
With this historical milestone in the books, the next phase of SpaceX’s stage return and reuse program began.
In the initial two days following the stage’s landing, SpaceX secured the stage and transported it to LC-39A at the Kennedy Space Center where it will now undergo a series of never-before performed rigorous inspections to see exactly how all of its systems held up during the launch and landing.
Once these inspections and refurbishments are complete, SpaceX will roll the first stage up the ramp of LC-39A and perform a static fire of the stage at the historic launch pad to see how the stage performs.
After the static fire, the stage will be extensively examined yet again to determine in detail the reuse strategy of Falcon 9 first stages as well as the cost-effectiveness of reuse.
(Images: via NASA, Orbital ATK, ULA SpaceX and L2 artist Nathan Koga – The full hi-res gallery of Nathan’s (SpaceX Dragon to MCT, SLS, Commercial Crew and more) L2 images can be *found here*)
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